Straddle carrier with slab and coil tongs

ABSTRACT

A self-propelled, steerable straddle carrier ( 10 ) includes a main frame ( 12 ) supported on transport wheels ( 14 ) with a tong table ( 20 ) and a plurality of hydraulic lift actuator ( 34 ) for raising and lowering the tong table ( 20 ) relative to the main frame ( 12 ). A pair of front and rear slab tongs ( 42, 44 ) are pivotally mounted on the tong table ( 20 ) with a pair of front and rear pinch cylinders ( 43, 45 ) for opening and closing the slab tongs ( 42, 44 ). A pair of coil tongs ( 52 ) arm disposed between the front and rear slab tongs ( 42, 44 ) with a pair of inverted yoke assemblies for pivotally supporting the coil tongs ( 52 ) and a center pinch cylinder ( 60 ) for opening and closing the coil tongs ( 52 ). A pair of hydraulic actuators ( 34 ) interconnect the yoke assemblies and the main frame ( 12 ) for raising and lowering the coil tongs ( 52 ) relative to the slab tongs ( 42, 44 ) to permit the straddle carrier ( 10 ) to transport either stacks of steel slabs or a steel coil.

This application is a 371 of PCT/US99/09895 filed May 6, 1999, whichclaims the benefit of Provisional of 60/084,570 filed May 7, 1998.

FIELD OF THE INVENTION

The present invention relates generally to vehicles for handling andcarrying heavy loads, and more particularly concerns an improvedstraddle carrier incorporating combined tongs for lifting, supportingand transporting both steel slabs and coils.

BACKGROUND OF THE INVENTION

U.S. Pat. Nos. 4,170,434, 4,488,848 and 4,601,630 to Kress et al.,assigned to the same assignee as the present invention, disclosevehicles that handle heavy loads. Vehicles constructed in accordancewith these patents have proven themselves in the field for reliably andefficiently handling the lifting and transporting of straddled loadsconsisting of steel slabs and billets on the order of 50-150 tons.

U.S. Pat. No. 5,496,146 to Thomas et al., and also assigned to the sameassignee as the present invention, discloses a slab and coil carrierwhich employs tongs for lifting, supporting and transporting steel slabsand a separate probe assembly, disposed generally between the tongs,which may be moved from an inactive storage position to an operativeposition for penetrating the open center of large steel coils. The probeis also elevatable with the tong supporting mechanism such that theprobe can lift, support and transport the steel coils from place toplace.

SUMMARY AND OBJECTS OF THE INVENTION

It is an object of the present invention to provide an improved straddletype carrier with combined tongs for lifting, supporting andtransporting both steel slabs and coils.

A further object is to provide such a straddle carrier with combinedslab and coil tongs which are mounted on a common tong table that can beraised and lowered to pick up or set down the steel slabs or coil.

A more detailed object is to provide means for vertically displacing theslab and coil tongs relative to each other so as to locate one set oftongs in a substantially out of the way inactive position when the otherset of tongs is operative for lifting, supporting and transporting aload of slabs or coil of steel.

These and other features and advantages of the invention will be morereadily apparent upon reading the following description of a preferredexemplified embodiment of the invention and upon reference to theaccompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a somewhat schematic side elevational view of a straddlecarrier incorporating the combined slab and coil carrying tongs of thepresent invention;

FIG. 2 is a schematic plan view of the straddle carrier shown in FIG. 1;

FIG. 3 is a front elevation of the straddle carrier shown in FIGS. 1 and2 with the slab tongs lowered and shown in both open (solid line) andclosed (broken line) positions while the coil tongs are shown in theiropen (solid line) position elevated with respect to the slab tongs; and,

FIG. 4 is an elevational view, similar to FIG. 3, but showing in thelower portion thereof the coil tongs lowered and shown in both open(solid line) and closed (broken line) positions while the slab tongs areshown in their open (solid line) position elevated with respect to thecoil tongs, and showing in the upper portion thereof the coil tongssupporting a steel coil for transport while the slab tongs are shown inan open inactive position.

While the invention will be described and disclosed in connection withcertain preferred embodiments and procedures, it is not intended tolimit the invention to those specific embodiments. Rather it is intendedto cover all such alternative embodiments and modifications as fallwithin the spirit and scope of the invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

Turning now to the drawings in more detail, there is shown in FIG. 1 aside elevation of a straddle carrier 10 which incorporates the featuresof the present invention. The straddle carrier 10 has a generallyrectangular main frame 12 supported adjacent the corners thereof byheavy duty ground engaging wheels 14. An operator's cab 16, shownschematically, is located at the forward end of the main frame 12 and anengine housing 18, also shown schematically, is supported at the toprear of the main frame 12. Preferably, each of the wheels 14 isself-propelled through a suitable hydraulic motor (not shown) driven bya pump (not shown) located in the engine housing 18. Each wheel 12 isalso preferably steerable and supports the main frame 12 through avertical pivot post 15 which may be rotated by suitable steeringmechanism (not shown) through suitable controls located in theoperator's cab 16.

As shown in FIG. 2, the rectangular main frame 12 is generally open inthe center to accommodate a vertically movable tong table 20, which inplan view, has a generally H-shaped configuration including front andrear transverse beams 22 and 24 interconnected by a pair ofspaced-apart, box-likes, center beams 26 and 28. The laterally extendingends of the front and rear beams 22, 24 each carries a verticallydisposed guide shoe 30 which moves up and down within the centralopening of the main frame 12 adjacent to and guided by a respectiveguide rail 32 attached to the inside of the main frame 12.

To raise and lower the tong table 20, the main frame 12 carries a pairof hydraulic actuators 34 on either side thereof positioned adjacent theends of the front and rear transverse beams 26 and 28. The upper end ofeach of the actuators 34 carries a pulley assembly 36 over which asuitable chain or cable, shown schematically at 38, is trained. One endof each cable 38, is secured to the main frame 12 and the other end ofthe cable is fastened to a respective one of the tong table guide shoes30. When the actuators 34 are retracted, as shown in FIG. 3, the tongtable 20 and guide shoes 30 are lowered within the central opening ofthe straddle carrier's main frame 12. When the actuators are extended,as shown in the upper portion of FIG. 4, the tong table and guide shoesare elevated to the upper load carrying and transport position.

In accordance with the present invention, the vertically elevatable tongtable 20 of the straddle carrier 10 carries a slab-gripping tongassembly 40 for lifting supporting and transporting a stack of steelslabs or the like, and the tong table 20 also carries a coil-grippingtong assembly 50 for lifting, supporting and transporting a coil ofsheet or strip steel. The slab tong assembly 40 includes front and rearpairs of slab tongs 42 and 44, with each pair of tongs including leftand right tong fingers 42 a, 42 b and 44 a, 44 b pivotally mounted onpins 46 carried by front and rear support plates 47 and 48 spacedoutwardly from the tong table transverse beams 22 and 24 and secured tothe tong table center beams 26 and 28. A pair of front and rearhydraulic pinch cylinders 43 and 45 interconnect the upper ends of theleft and right tong fingers 42 a, 42 b and 44 a, 44 b of each slab tongpair 42 and 44.

When the pinch cylinders 43 and 45 are retracted, as shown in FIG. 3,the lower end of the tong fingers 42 a, 42 b (and 44 a, 44 b) are opento the solid line position to receive or discharge a stack of steelslabs, shown diagrammatically at S. When the pinch cylinders 43, 45 areextended, the lower ends of the slab tong fingers 42 a, 42 b (and 44 a,44 b) are pivoted toward the closed position, as shown in broken linesin FIG. 3. Of course, if the straddle carrier 10 is positioned tostraddle a stack of steel slabs S, as shown diagrammatically in FIG. 3,the lower ends of the slab tong fingers 42 a, 42 b (and 44 a, 44 b)would close, engage and grip the steel slabs. Once the stack of steelslabs is gripped by the slab tongs 42 and 44, the hydraulic liftactuators 34 can be energized to elevate the tong table 20, the slabgripping tong assembly 40 and the stack of steel slabs S.

Pursuant to the invention, the coil gripping tong assembly 50 includes apair of coil tongs 52 mounted between the front and rear pairs of slabtongs 42 and 44. Each of the coil tongs 52 includes a center web portion53 reinforced by fore and aft edge flanges 54 a and 54 b which arepivotally mounted by pins 56 on the lower ends of a pair of front andrear yoke assemblies 57 and 58, each having a generally invertedU-shaped configuration. In the preferred embodiment, the upper ends ofthe coil tong flanges 54 a, 54 b are angled upwardly and inwardly towardthe transverse center line of the straddle carrier 10. The upper ends ofthe right hand coil tong flanges 54 a and 54 b are connected together bya pin which also pivotally connects the right hand end of a centerhydraulic pinch cylinder 60. Similarly, the upper ends of the left handcoil tong flanges 54 a and 54 b are pin connected together to the lefthand end of the center hydraulic pinch cylinder 60.

In keeping with the invention, the front and rear coil tong supportingyokes 57, 58 are connected to the free ends of a pair of front and rearyoke elevating cylinders 62, 64 which have their base ends secured tothe center box beams 26, 28 of the tong table 20. Preferably, theelevating cylinders 62, 64 are in the form of multiple stage hydrauliccylinders. When the yoke elevating cylinders 62, 64 are extended, asshown in FIG. 3, the coil tong assembly 50 is raised relative to theslab tong assembly 40. Also, when the center pinch cylinder 60 isretracted, as also shown in FIG. 3, the lower ends of the coil tongs 52are pivoted to their open or inactive position. Thus, as seen in FIG. 3,the coil tongs 52 may be opened and elevated relative to the slab tongfingers 42, 44 so that the slab tong fingers are operative to grip andhold a stack of steel slabs S.

When it is desired to pick up and transport a coil C of strip steel orother metal, the straddle carrier 10 is positioned over the steel coilC, as shown diagrammatically in the lower portion of FIG. 4. To provideclearance for the coil C between the coil tongs 52, the yoke elevatingcylinders 62, 64 are retracted which has the effect of raising the slabtong assembly 30 out of the way of the coil tong assembly 40. Thus, asseen in the lower portion of FIG. 4, the coil tongs 52 are lowered andopened to receive the coil C and the slab tong fingers 42 a, 42 b areopened and raised to provide clearance for the coil C.

To grip the coil C, the center pinch cylinder 60 is activated to closethe coil tongs 52 around the coil C. If the coil is relatively small indiameter, the lower ends of the coil tongs 52 may be pivoted together toa closed (broken line) position with their ends together. To raise thecoil C to transport position, the lift actuators 34 are extended whichelevates the tong table 20 and the tong assemblies 40 and 50 and thecoil C to the position shown in the upper portion of FIG. 4.

Thus it will be seen that a novel and improved straddle carrier withcombined slab and coil tongs has been provided which attains theaforementioned objects. By nesting the coil tong assembly 50 between thefront and rear pairs of slab tongs 42, 44 and by pivoting the coil tongson elevatable yokes supported on extendable and retractable hydraulicactuators, the slab tongs 42, 44 and the coil tongs 52 may be raised andlowered relative to one another to position one tong assembly out of theway while the other tong assembly is operative to grip, support andtransport its respective load, Various additional modifications of theembodiments specifically illustrated and described herein will beapparent to those skilled in the art, particularly in light of theteachings of this invention. The invention should not be construed aslimited to the specific form shown and described, but instead is setforth in the following claims.

What is claimed is:
 1. A self-propelled, steerable straddle carriercomprising, in combination, a main frame supported on transport wheels,a tong table, a plurality of hydraulic lift actuators for raising andlowering the tong table relative to the main frame, pairs of front andrear slab tongs pivotally mounted respectively on the front and rear oftong table, front and rear pinch cylinders for opening and closing thefront and rear slab tongs, a pair of coil tongs disposed between thefront and rear slab tongs, a pair of inverted yoke assemblies forpivotally supporting the coil tongs, a center pinch cylinder for openingand closing the coil tongs, and a pair of actuators interconnecting theyoke assemblies and the tong table for raising and lowering the coiltongs relative to the slab tongs and the tong table.
 2. A straddlecarrier as defined in claim 1 wherein the center pinch cylinder isoperable for opening lower ends of the coil tongs substantially equal tothe maximum opening between the lower ends of the slab tongs when thefront and rear pinch cylinders are retracted.
 3. A straddle carrier asdefined in claim 2 wherein the hydraulic lift actuators are operable forraising the tong table, the slab tongs and the coil tongs so as to lifta stock of metal slabs to transport position.
 4. A straddle carrier asdefined in claim 1 wherein the hydraulic lift actuators are operable forraising the tong table and the opened slab tongs a substantial distanceabove the ground while lower ends of the opened coil tongs arepositioned substantially in engagement with the ground so as to form atunnel-like opening for receiving a large coil of metal.
 5. A straddlecarrier as defined in claim 4 wherein the center pinch cylinder isoperable for closing the lower ends of the coil tongs to substantiallyencircle a large coil of metal.
 6. A straddle carrier as defined inclaim 5 wherein the hydraulic lift actuators are operable for raisingthe tong table, the slab tongs and the coil tongs so as to lift themetal coil to transport position.